1. Technical Field
The present invention relates to an eyeglass lens including a plurality of areas having different powers, and to a design method, a manufacturing method and a design system for such an eyeglass lens.
2. Related Art
In design of eyeglass lens having a progressive power zone, a meridian is defined by considering movement of a visual line of a wearer from distance vision to near vision, and a clear vision area having a small level of distortion and shaking of an image is set with respect to the defined meridian. Concrete examples of eyeglass lenses designed as described above are disclosed, for example, in Japanese Patent Provisional Publication Nos. 2004-191757A (hereafter, referred to as “patent document 1”), HEI 10-123467A (hereafter, referred to as “patent document 2”) and HEI 9-251143A (hereafter, referred to as “patent document 3”).